1. Field of the Invention
The present invention relates generally to a coordinates indication device, and a coordinates measurement device for measuring an input position of the coordinates indication device, and more particularly, to a finger or a coordinates indication device, such as a stylus pen, and a coordinates measurement device for measuring an input position of the finger or the coordinates indication device.
2. Description of the Related Art
Along with the recent rapid growth of smart phones or tablet Personal Computers (PCs), built-in devices for measuring the positions of touches on the smart phones or tablet PCs have been extensively developed. A smart phone or a tablet PC is usually equipped with a touch screen on which a user designates specific coordinates using his or her finger or a stylus pen, and may thus input a specific signal to the smart phone or tablet PC.
Touch screens may operate in an electrical, infrared, or ultrasonic wave fashion. A Resistive (R-type) touch screen and a Capacitive (C-type) touch screen are examples of an electrically-operating touch screen. Previously, the R-type touch screen that can recognize inputs of a user's finger and a stylus pen simultaneously was the most popular. However, the R-type touch screen suffers from problems caused by reflection from an air gap between Indium Tin Oxide (ITO) layers. Specifically, the transmittance of light transmitted through a display is decreased and external light reflection is increased due to the air gap between the ITO layers in the R-type touch screen.
Accordingly, the C-type touch screen has recently gained popularity. The C-type touch screen operates by sensing the difference between the capacitances of transparent electrodes generated by an object's touch. Although the C-type touch screen can relatively accurately sense the position of an object touching a large area such as a finger, it has difficulty in accurately sensing the position of an object, such as a stylus pen, touching a small area. Moreover, the C-type touch screen cannot physically distinguish a hand or finger from a stylus pen, thereby causing an operation error in regard to an unintended hand touch.
To prevent the above-described operation error by more accurately sensing the touched position of a stylus pen, an ElectroMagnetic Resonance (EMR) position measurement device is conventionally used in addition to the C-type touch screen. However, the additional use of the EMR position measurement device leads to an increase in the volume, weight, and cost of the smart phone or tablet PC.
Accordingly, there exists a need for developing a technique which determines the input position of an object, such as a stylus pen, without an operation error, even though an additional element such as an EMR sensor is not used.